Documentation in modules/pam_succeed_if/* assumes that user accounts start at ID
500; please update it to refer to /etc/login.defs [UG]ID_MIN, we plan to change the boundary.
Version-Release number of selected component (if applicable):
pam-1.1.3-10.fc16

Frankly, I do not see any mention of system accounts in the pam_succeed_if documentation. The number 500 is there just as an arbitrary number. As pam_succeed_if does not read login.defs and I do not plan to make it to do so it does not make sense to mention it in the pam_succeed_if documentation.